A resin containing a constituent unit derived from ethylene and a constituent unit derived from an α-olefin (hereinafter also referred to as ethylene-α-olefin copolymers) is a material used in a wide range of application fields such as electrophotographic toners and hot melt compositions for hot melt adhesives.
An ethylene-α-olefin copolymer is used in combination with a variety of resins. For example, the ethylene-α-olefin copolymer can be combined with a toner binder resin for use in an image forming toner. Further, the ethylene-α-olefin copolymer can be blended with a resin imparting desired properties thereto for use as a hot melt composition for a hot melt adhesive.
It is known that when a resin composition containing a non-polar wax, such as a low-molecular weight polyethylene wax or a low-molecular weight polypropylene wax, is used for a toner, occurrence of offsetting becomes less, i.e., so-called offset resistance becomes improved (PTLs 1 and 2).
Offsetting is an undesired transfer of toner to an image section which occurs as follows. When a toner transferred to paper from an image developed on a photoreceptor or a toner adhered directly onto paper having a photosensitive layer formed thereon is brought into contact with a heating element for the fixation of the toner, part of the toner adheres to the surface of the heating element and the adhered toner is transferred to the subsequent image section. It is considered that addition of a non-polar wax (such as a low-molecular weight polyethylene wax or a low-molecular weight polypropylene wax) to a toner imparts releasability from a heating element and this results in decrease of the occurrence of offsetting.
As a wax for improving the offset resistance, use of an ethylene-1-butene copolymer wax has been proposed (PTLs 1 and 2).